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1/*
2 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#define DEBUG
14
15#include <linux/fs.h>
16#include <linux/magic.h>
17#include <linux/mount.h>
18#include <linux/init.h>
19#include <linux/user_namespace.h>
20
21#include "sysfs.h"
22
23static struct kernfs_root *sysfs_root;
24struct kernfs_node *sysfs_root_kn;
25
26static struct dentry *sysfs_mount(struct file_system_type *fs_type,
27 int flags, const char *dev_name, void *data)
28{
29 struct dentry *root;
30 void *ns;
31 bool new_sb;
32
33 if (!(flags & MS_KERNMOUNT)) {
34 if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
35 return ERR_PTR(-EPERM);
36
37 if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
38 return ERR_PTR(-EPERM);
39 }
40
41 ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
42 root = kernfs_mount_ns(fs_type, flags, sysfs_root,
43 SYSFS_MAGIC, &new_sb, ns);
44 if (IS_ERR(root) || !new_sb)
45 kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
46 return root;
47}
48
49static void sysfs_kill_sb(struct super_block *sb)
50{
51 void *ns = (void *)kernfs_super_ns(sb);
52
53 kernfs_kill_sb(sb);
54 kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
55}
56
57static struct file_system_type sysfs_fs_type = {
58 .name = "sysfs",
59 .mount = sysfs_mount,
60 .kill_sb = sysfs_kill_sb,
61 .fs_flags = FS_USERNS_MOUNT,
62};
63
64int __init sysfs_init(void)
65{
66 int err;
67
68 sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
69 NULL);
70 if (IS_ERR(sysfs_root))
71 return PTR_ERR(sysfs_root);
72
73 sysfs_root_kn = sysfs_root->kn;
74
75 err = register_filesystem(&sysfs_fs_type);
76 if (err) {
77 kernfs_destroy_root(sysfs_root);
78 return err;
79 }
80
81 return 0;
82}
1/*
2 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#define DEBUG
14
15#include <linux/fs.h>
16#include <linux/mount.h>
17#include <linux/pagemap.h>
18#include <linux/init.h>
19#include <linux/module.h>
20#include <linux/magic.h>
21#include <linux/slab.h>
22
23#include "sysfs.h"
24
25
26static struct vfsmount *sysfs_mnt;
27struct kmem_cache *sysfs_dir_cachep;
28
29static const struct super_operations sysfs_ops = {
30 .statfs = simple_statfs,
31 .drop_inode = generic_delete_inode,
32 .evict_inode = sysfs_evict_inode,
33};
34
35struct sysfs_dirent sysfs_root = {
36 .s_name = "",
37 .s_count = ATOMIC_INIT(1),
38 .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
39 .s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
40 .s_ino = 1,
41};
42
43static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
44{
45 struct inode *inode;
46 struct dentry *root;
47
48 sb->s_blocksize = PAGE_CACHE_SIZE;
49 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
50 sb->s_magic = SYSFS_MAGIC;
51 sb->s_op = &sysfs_ops;
52 sb->s_time_gran = 1;
53
54 /* get root inode, initialize and unlock it */
55 mutex_lock(&sysfs_mutex);
56 inode = sysfs_get_inode(sb, &sysfs_root);
57 mutex_unlock(&sysfs_mutex);
58 if (!inode) {
59 pr_debug("sysfs: could not get root inode\n");
60 return -ENOMEM;
61 }
62
63 /* instantiate and link root dentry */
64 root = d_alloc_root(inode);
65 if (!root) {
66 pr_debug("%s: could not get root dentry!\n",__func__);
67 iput(inode);
68 return -ENOMEM;
69 }
70 root->d_fsdata = &sysfs_root;
71 sb->s_root = root;
72 return 0;
73}
74
75static int sysfs_test_super(struct super_block *sb, void *data)
76{
77 struct sysfs_super_info *sb_info = sysfs_info(sb);
78 struct sysfs_super_info *info = data;
79 enum kobj_ns_type type;
80 int found = 1;
81
82 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
83 if (sb_info->ns[type] != info->ns[type])
84 found = 0;
85 }
86 return found;
87}
88
89static int sysfs_set_super(struct super_block *sb, void *data)
90{
91 int error;
92 error = set_anon_super(sb, data);
93 if (!error)
94 sb->s_fs_info = data;
95 return error;
96}
97
98static void free_sysfs_super_info(struct sysfs_super_info *info)
99{
100 int type;
101 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
102 kobj_ns_drop(type, info->ns[type]);
103 kfree(info);
104}
105
106static struct dentry *sysfs_mount(struct file_system_type *fs_type,
107 int flags, const char *dev_name, void *data)
108{
109 struct sysfs_super_info *info;
110 enum kobj_ns_type type;
111 struct super_block *sb;
112 int error;
113
114 info = kzalloc(sizeof(*info), GFP_KERNEL);
115 if (!info)
116 return ERR_PTR(-ENOMEM);
117
118 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
119 info->ns[type] = kobj_ns_grab_current(type);
120
121 sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
122 if (IS_ERR(sb) || sb->s_fs_info != info)
123 free_sysfs_super_info(info);
124 if (IS_ERR(sb))
125 return ERR_CAST(sb);
126 if (!sb->s_root) {
127 sb->s_flags = flags;
128 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
129 if (error) {
130 deactivate_locked_super(sb);
131 return ERR_PTR(error);
132 }
133 sb->s_flags |= MS_ACTIVE;
134 }
135
136 return dget(sb->s_root);
137}
138
139static void sysfs_kill_sb(struct super_block *sb)
140{
141 struct sysfs_super_info *info = sysfs_info(sb);
142 /* Remove the superblock from fs_supers/s_instances
143 * so we can't find it, before freeing sysfs_super_info.
144 */
145 kill_anon_super(sb);
146 free_sysfs_super_info(info);
147}
148
149static struct file_system_type sysfs_fs_type = {
150 .name = "sysfs",
151 .mount = sysfs_mount,
152 .kill_sb = sysfs_kill_sb,
153};
154
155int __init sysfs_init(void)
156{
157 int err = -ENOMEM;
158
159 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
160 sizeof(struct sysfs_dirent),
161 0, 0, NULL);
162 if (!sysfs_dir_cachep)
163 goto out;
164
165 err = sysfs_inode_init();
166 if (err)
167 goto out_err;
168
169 err = register_filesystem(&sysfs_fs_type);
170 if (!err) {
171 sysfs_mnt = kern_mount(&sysfs_fs_type);
172 if (IS_ERR(sysfs_mnt)) {
173 printk(KERN_ERR "sysfs: could not mount!\n");
174 err = PTR_ERR(sysfs_mnt);
175 sysfs_mnt = NULL;
176 unregister_filesystem(&sysfs_fs_type);
177 goto out_err;
178 }
179 } else
180 goto out_err;
181out:
182 return err;
183out_err:
184 kmem_cache_destroy(sysfs_dir_cachep);
185 sysfs_dir_cachep = NULL;
186 goto out;
187}
188
189#undef sysfs_get
190struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
191{
192 return __sysfs_get(sd);
193}
194EXPORT_SYMBOL_GPL(sysfs_get);
195
196#undef sysfs_put
197void sysfs_put(struct sysfs_dirent *sd)
198{
199 __sysfs_put(sd);
200}
201EXPORT_SYMBOL_GPL(sysfs_put);